>>You are right that one can conceive that malanism in peppered moths was>induced by some as yet unidentified environmental influence. (I assume,>since malanism is heritable, that that environmental influence also>triggered the particular mutation for malanism.)>

Melanism is caused by a gene; in the peppered moth it appears as the result
of a mutation (normally the moth would not have the gene). It is possible
for pollution to trigger mutations, but it is generally not that specific
(the normal result is cancer or some other disease, not melanism), nor that
limited (induction by pollution should have produced other observable
mutations as well). In any event, in the absence of a mechanism, any
discussion of induction is moot.